FOLSOM, Calif. — For three days in a row last week, California broke all-time electricity consumption records as the mercury climbed over 90 degrees across much of the state.

And this is only July. Sizzling August still lies ahead, and the record is almost certain to be broken again.

“We still haven’t seen our peak for this year,” said Jim Detmers, acting chief operating officer of the Independent System Operator, manager of much of California’s power grid.

The first statewide heat wave of the year has stirred fears of blackouts in California four years after the power system collapsed under the weight of high demand, market manipulation, a botched attempt at deregulation, and inadequate generation and transmission capacity.

Industry experts, citing improvements in transmission lines and the construction of new power plants, said a repeat of the rolling blackouts of 2001 is unlikely this summer.

Nevertheless, California’s power market is still in flux, transmission bottlenecks persist, and customers have been falling out of the habit of conserving. Not only that, but California’s reservoirs are lower than usual, which means there will be less hydroelectric power later this summer, when demand is highest.

And the wild card, as usual, is wildfires. They can take down transmission lines at the worst possible time, just when temperatures are soaring in late summer.

“As summer progresses, our reserves get tighter and tighter, the margins get thinner and thinner,” said Jim McIntosh, director of ISO’s grid operations. “When in you’re in that situation, it only takes one event” to cause a crisis.

Or as Jan Smutny-Jones, executive director of the Independent Energy Producers, put it: “Generally, blackouts aren’t a result of one thing. It’s not the first or the second thing, but the third event. That’s when you get into trouble.”

Gov. Arnold Schwarzenegger planned to meet with business leaders Tuesday to urge them to volunteer for programs under which companies get a price break on power if they agree to curtail their electricity use when grid managers call of them.

On July 19, California broke the all-time record for power use, set in 1999, and then broke the new mark the next day, and did it again the day after that, when the amount of electricity surging through the grid reached 44,360 megawatts. At the same time, the state’s power managers had to close seven major transmission lines threatened by a Southern California forest fire.

To cope with the crisis, officials asked people to scale back their electricity use until the evening. But the lights stayed on, and the ISO did not even have to issue an emergency warning of low reserves.

For all the drama last week, the temperatures were not as high as they were when the previous records were set. In other words, California’s power usage was off the charts not because the temperature was off the charts, but because Californians are using more electricity.

Energy officials had projected a 3.5 percent increase in demand over the past year, but are seeing a 6.6 percent gain, mostly because of economic growth.

Since the 2001 crisis, California has added 8,300 megawatts to the grid, and many of the long-term contracts the state signed in 2001 are still bringing a steady supply of power. The California Energy Commission has approved about 10,000 more megawatts of power, but those plants are awaiting financing.

Still, some transmission problems remain, such as in Southern California. There, three new plants just over the Mexican border can generate about 1,600 megawatts, but crowded power lines can import only about 400 megawatts, McIntosh said.

The state’s most notorious bottleneck is an 84-mile stretch of high-voltage lines that run between Northern and Southern California. An extra line that will allow an additional 1,500 megawatts to flow between the two regions is being added but will not be completed until the end of the year.

During the electricity crisis, conservation trimmed 14 percent from the state’s energy use, ISO spokeswoman Stephanie McCorkle said. Those habits have largely tapered off, said Suzanne Garfield with the California Energy Commission, though some effects are still felt, mostly because so many consumers bought energy-efficient appliances.